KR20010089876A - Cold plate for a metallurgical furnace - Google Patents

Abstract

PURPOSE: A cooling plate whose one side facing the inside of an oven is applied with a coating layer having lower thermal conductivity than copper base material that is main constituent of the cooling plate is provided to ensure superior dimensional stability over sever operation conditions. CONSTITUTION: Cooling plate consists of copper or a copper alloy and has coolant channels. The side of the cooling plate facing the inside of the oven has a coating layer having a lower thermal conductivity than the copper base material. The coating has a heat conductivity lower than 320, preferably less than 10 W/(m·K). The coating is made from a material based on zirconium oxide containing yttrium oxide as an additive.

Description

Cold plate for smelting furnace {COLD PLATE FOR A METALLURGICAL FURNACE}

The present invention is a component of a furnace wall of a smelting furnace, such as a blast furnace or a blast furnace, and is composed of copper or a copper alloy, and relates to a cooling plate through which a refrigerant channel passes.

In smelting furnaces, furnace walls were installed in many furnace zones until several years ago with water-cooled cold plates made of gray cast iron or steel. This material has a relatively low thermal conductivity. Copper or copper alloys have substantially better thermal conductivity than gray cast iron or steel. A cold plate made of copper has a refrigerant channel formed therein, for example by mechanical deep hole drilling, which extends almost parallel to the furnace wall.

Due to the high thermal stress on the side of the cold plate towards the inner space of the furnace, the cold plate changes its mechanical properties.

At this time, the following characteristic change occurs. In other words,

-Locally reduced hardness,

-Locally changed grain size or microstructure,

Macroscopically observable deformation due to creep propagation of the material caused by asymmetric thermal expansion.

According to the furnace operation method, the thermal stress of the cold plate is generally not constant over time. This fluctuating thermal stress creates a temporally varying temperature profile inside the wall of the cold plate, thus changing the internal stress on the material of the cold plate.

This fluctuating stress is combined with the risk of material fatigue (eg material destruction by cracking), which can jeopardize furnace operations. This risk is still increased by causing a change in the above-described material properties in addition to the variable thermal stress.

Considered in the prior art to eliminate this drawback is to improve the cooling of the furnace wall, for example through structural changes to the cooling channels. The interior of the furnace is thereby significantly cooled in the wall area, thus removing the thermal stress.

It is an object of the present invention to provide a cold plate which allows for a long service life by reliably providing improved dimensional stability across all operating situations starting from the prior art.

To achieve this object, the present invention proposes to provide at least one coating layer on the side of the cold plate facing the interior of the furnace, which coating layer has a lower thermal conductivity than the copper base material.

In this way, the cooling action of the cold plate acting inside the furnace is reduced, and considering the operation of the furnace as a whole has a surprising advantage.

In addition, the core of the present invention is to reduce unwanted cold plate variations by reducing the thermal stress of the cold plate. To this end, the cold plate is provided with a coating layer suitable for the side of the cold plate facing the inner space of the furnace.

This coating layer may be formed of one or more layers, and the individual layers may have different configurations.

The coating layer (s) is preferably applied by a spraying method such as plasma spraying or flame spraying.

Thus, at least one of these layers functions as an insulating layer or a heat insulating layer and has a lower thermal conductivity than the copper base metal.

According to the present invention, the thermal conductivity of the coating layer should be less than 320 mW / (m · Ｋ). This thermal conductivity may be less than 10 kW / (m · kPa), particularly in the case where a strong insulating action is required.

Preferably, the thermal insulation layer can consist of a metal or a metal-non-metal combination. On the other hand, this heat insulating layer can be composed of a mixture or compound of metal and metal-non-metal combinations.

For example, the thermal insulation layer can be formed of any material on the zirconium-oxide base material, which material advantageously contains yttrium-oxide as an additive.

The coating layer may be used with an insulating layer inherent in the base material or with other constructions that improve the bonding of the insulating layer apparatus, such as the McLaLＹ coating layer, where "M" is a metal, such as Fe, Ni, CO or these elements. Compound.

In addition, it is advantageous to roughen the base metal before coating to better bond the coating layer to the base metal.

It is advantageous to make the thickness of the whole coating layer into the range of 0.1-1.5 mm.

According to the application, particular advantages arise from the application of various parts of the furnace side cold plate surface to the coating layer, or of varying layer thicknesses for various cold plate regions.

In many furnaces, due to the various interactions (bonding, melting behavior of furnace slag, chip behavior of furnace slag, or coating layer), the coating material sprayed on the surface of the cold plate in the interior space of the furnace with the various furnace slag, It is even more advantageous to provide a thicker coating layer on the surface, in particular in the area of the plate which additionally protrudes into the furnace space, than the smaller and wider protruding edges.

According to the present invention, by providing at least one coating layer composed of copper or a copper alloy and having a lower thermal conductivity than that of a copper base material on the side facing into the furnace of the cooling plate through which the refrigerant channel passes, it is possible to cover all furnace operation situations. Improved dimensional stability and thus long life.

Claims (6)

It is a component of the furnace wall of a smelting furnace, such as a blast furnace or a blast furnace, consists of copper or a copper alloy, and is a cooling plate through which a refrigerant channel passes, Cooling plate of the smelting furnace, the side of the cooling plate facing the interior of the furnace is provided with at least one coating layer having a lower thermal conductivity than the copper base material. The cooling plate of a smelting furnace according to claim 1, wherein the coating layer has a thermal conductivity of less than 320 mW / (m · k), preferably less than 10 mW / (m · k). The cooling plate of the smelting furnace according to claim 1 or 2, wherein the coating layer has a thickness in the range of 0.1 to 1.5 mm. The cooling plate of the smelting furnace according to any one of claims 1 to 3, wherein each of the coating layers is applied by a thermal spraying method. The cooling plate according to any one of claims 1 to 4, wherein the coating layer is made of a predetermined material on the zirconium oxide base material, preferably containing yttrium oxide as an additive. 6. The method of any one of claims 1 to 5, wherein at least one interlayer is disposed between the copper base material and the coating layer to improve bonding, wherein the interlayer consists essentially of MCRCA, wherein "M" is a metal. And, preferably, the cooling plate of the smelting furnace comprising at least one element consisting of Fe, Ni, or CO series.